Cranes are commonly used to lift heavy objects in various types of construction projects. Many of these cranes are mounted on a chassis or vehicle of some type. These cranes typically have a boom mounted to a rotatable base. Often times the boom is telescopic and can be extended and retracted. Similarly the boom can be raised and lowered by increasing or decreasing the angle between the boom and that of the base.
One of the most common hazards of operation of such a crane is lifting too large of a load. Often times it is not the actual weight of the load being lifted that causes the failure. It is that the load being lifted is at a distance too far from the base.
An example of this might be a load that is initially lifted from adjacent the chassis of the crane. Once lifted, the crane then booms out or lowers the boom, causing the load to move out away from the base of the crane. At the same time the operator may extend the telescoping boom thus adding to the distance between the load and the base of the boom. While the weight of the load in this example remains constant, the moment created by the load increases as the distance between the load and the base of the boom increases. At the point this crane moment load exceeds that of what the crane is designed to handle, the crane will roll over presenting the possibility of damage to the load as well as damaging surrounding structures and injuring nearby workers.
While accidents like this occur regularly, prior attempts to implement safeguards have been limited to crane operating systems which monitor the weight of the load or hydraulic system pressure created by the load. This is a key variable in the problem. However as can be seen by the example above, what begins as a lift which is well within the capacity of the crane can have devastating results when the load is moved too far away from the boom base.
Another key variable that can drastically impact the safe working radius of the crane is the incline of the surface supporting the crane chassis and in turn the incline of the chassis itself. A slight gentle incline can have a profound effect on the safe operating radius of the crane. Often times these inclines go unnoticed by the crane operator.
Therefore what is needed is a crane operating system which monitors the operational variables of the crane that effect the crane moment load and vehicle stability.
Further what is needed is a crane operating system which monitors the crane moment load in combination with the ability to restrict the operation of the crane to movements within its capacity.
Additionally what is needed is a crane operating system which considers such factors as boom rotation and inclination, outrigger location, chassis incline and boom raising cylinder hydraulic pressure in keeping the crane within the safe operating envelope.